What dish is a good indication of cooking competence
A proper medium rare steak? Omelet?
I would say can feed 1-6 with strange time, budget, ingredient constraints. Anyone can read a recipe and plan, but it takes a good cook to sub on the fly and still have it be edible
i'd say making REALLY delicious bread is a tough one. baguettes or croissants.
other than that, it's as simple as searching a recipe, trying it out, change what you want to change, keep developing and tweeking it it untill it's perfect for your taste. bam. your own "secret recipe" and everybody thinks you are a kitchen-god
That's what Gordon Ramsay said when asked.
You're on the right track, OP. I think it should be a quick bread like biscuits or some kind of pasta or noodles, though. It should be part of a bigger meal.
A competent cook should be able to whip something up fairly quickly using basic ingredients.